Explosive slurry having constant detonation velocity over a wide temperature range

ABSTRACT

AN AQUEOUS EXPLOSIVE SLURRY IS PROVIDED HAVING A CONSTANT DETONATION VELOCITY OVER A WIDE TEMPERATURE RANGE, AND SENSITIVE ENOUGH TO BE DETONATED IN A FILM OR LAYER FROM 1/4 TO 1/2 INCH THICK, BASED ON PRIMARY HIGH EXPLOSIVE SUCH AS PENTOLITE, NITROSTARCH OR PENTAERYTHRITOL TETRANITRATE, AN INORGANIC NITRATE OXIDIZER, AN AMIDE FORMING A EUTECTIC MIXTURE WITH INORGANIC NITRATES, AND A WATER-SOLUBLE THICKING AGENT, IF DESIRED, TO ADJUST THE VISCOSITY OF THE SLURRY.

United States Patent 3,676,234 EXPLOSIVE SLURRY HAVING CONSTANT DET- ONATION VELOCITY OVER A WIDE TEM- PERATURE RANGE William L. Schwoyer, Yardley, Pa., assignor to Commercial Solvents Corporation, New York, N. No Drawing. Filed Dec. 9, 1969, Ser. No. 883,632

Int. Cl- C06b /00 US. Cl. 149-38 19 Claims ABSTRACT OF THE DISCLOSURE This invention relates to aqueous explosive slurries having a constant velocity over a wide temperature range, and capable of being shot in films or layers of from A to /2 inch thick, based on a high explosive sensitizer, an inorganic nitrate oxidizer, a eutectic-forming amide, a thickener, and water.

The recently developed art of explosive bonding of metals has created a demand for explosives in which the energy given otf is closely controlled within narrow limits. The reason is that it is important to match the velocity of the detonation waves created by the explosive to the sonic velocity of the metals being bonded. If the velocity of the shock wave is higher than the sonic velocity of the metal, damage to the metal structure can result. On the other hand, if the velocity is too low, then good bonding is not obtained.

Several types of explosives have been proposed for the bonding of metals, including sheet, cast, powdered and slnrried explosives.

Sheet explosives can be made in thin layers, but they require a high energy explosive, such as RDX or PETN, in order to be sufliciently sensitive to be detonable in inch to 1 inch layers. Such explosives inherently have a high velocity and it has been found virtually impossible to lower the velocity of the explosive sufliciently to match the sonic velocity of the metal. The available sheet explosives are without exception of too high a velocity for the bonding of most metals. In order to reduce the velocity of the detonating wave so as to avoid damage to the metal structure, it is necessary to interpose sheet materials of varying types between the explosive sheet and the metal to be bonded. These rupture and so interfere with and reduce the velocity of the shock wave. This, however, is an empirical and inaccurate technique, at best, since the effect of the sheet is entirely unpredictable, and requires much trial and error to determine the type of sheets and their thickness for any particular bonding purpose. Besides slowing the bonding operation down, the trial-and-error approach does not make possible control of the velocity within the tolerances required for good bonds. Moreover, sheet explosives are rather costly, and the necessity of making a number of wasteful trial detonations increases the cost of the operation.

Cast explosives also have high velocities, and their physical nature is such that it is virtually impossible to form them in thin inch to 1 inch layers, as required for metal bonding.

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Explosive powders can be formed in such thin layers, but in order to obtain the proper velocities, they must be mixed with water-soluble inorganic nitrates, which are hygroscopic and pose a physical handling problem in wet atmospheres, or with inert materials. If the powder is to be used in a large surface area, it is hard to maintain uniformity in the layer thickness, so as to obtain the prescribed velocity everywhere in the layer, and this means that bonds of uneven strength and quality are obtained.

Aqueous explosive slurries can be formed in films that have a uniform loading density, but they are difficult to formulate so as to have sufiicient sensitivity to detonate in the thin layer thicknesses of the order of 4 inch to 1 inch required to impart the needed energy for bonding. Also, explosive slurries also have a higher velocity than the sonic velocity of most metals. Moreover, they undergo a large change in velocity with temperature, due to changes in the density of the slurry. This is a consequence of the great change in solubility of inorganic nitrates with temperature, and this means that unless the bonding is carried out at the same temperature every time, it is quite difficult to duplicate previously obtained results, and obtain uniform bonding.

In accordance with the invention, aqueous explosive slurries are provided that are capable of detonation with aconstant velocity over a wide temperature range, preferably, within the range from about 25 to about F., encompassing virtually all of the temperatures that would normally be employed in explosive bonding. These explosive slurries, moreover, can be formulated to have any required velocity that is below the sonic velocity of the metal. By appropriate adjustment in accordance with. the invention, it is possible to formulate explosive slurries that have a constant velocity matching the sonic velocity of any type of metal to be bonded within the range from approximately 15,000 to approximately 20,000 feet per second. These explosive slurries, moreover, sustain propagation in quite thin layers, within the range from inch to 1 inch thick, and maintain constant velocity at such layer thicknesses.

By constant velocity, it is meant that the velocity of the explosive slurry over the stated temperature range does not vary more than i250 feet per second, which is virtually the experimental error in measuring velocity, using most detection equipment.

The aqueous slurries in accordance with the invention are based on a high explosive sensitizer, such as pentolite, nitrostarch or PETN, an inorganic nitrate oxidizer, an organic amide that forms eutectic mixtures with inorganic nitrates, and optionally, an inorganic coolant, as well as one or more thickeners to adjust the viscosity of the slurry to within the desired range, and maintain a thin layer in the working location.

In the aqueous slurries of the invention, all of the inorganic nitrate oxidizer is in solution throughout the temperature range within which the velocity of the slurry is constant. This prerequisite is ensured by so formulating the slurry that at the lowest temperature that is likely to be encountered at detonation, the amount of the inorganic nitrate oxidizer present is completely soluble in the amount of free water in the slurry. The aqueous inorganic nitrate solution at this temperature can be a saturated solution of the inorganic nitrate, but it need not be. However, since the amount of water preferably approximates the minimum needed to dissolve the inorganic nitrate, it preferably is a saturated or nearly saturated solution.

As the inorganic nitrate oxidizer there can be employed any inorganic nitrate. Exemplary are ammonium nitrate, the alkali metal nitrates, for example, sodium nitrate and potassium nitrate, the alkaline earth metal nitrates, such 3 as calcium nitrate, barium nitrate and strontium nitrate, and mixtures thereof. Ammonium nitrate is preferred, and mixtures of ammonium nitrate and sodium nitrate are particularly useful.

The particular inorganic nitrate or nitrates used and the relative proportions of the nitrates in the mixture are selected to obtain a slurry density within a desired range. Control of density affords a means with other parameters of controlling or obtaining a velocity of a selected magnitude, and can be adjusted as desired by such a selection of the available inorganic nitrates.

Inasmuch as the inorganic nitrate oxidizer is in solution, its crystalline form is of no consequence, except as its solubility can affect the amount that can be dissolved initially in forming the slurry. Mill, prill and granular inorganic nitrates are satisfactory. Any of the hydrated forms can be used as Well. However, inorganic nitrates free from Water-insoluble coatings or films, applied occasionally to control hygroscopicity, are preferred.

As the explosive sensitizer, it is necessary to employ a sensitizer that imparts a sufficient sensitivity to the slurry so that it accepts and sustains detonation in a layer of from A to 1 inch in thickness. The preferred objective is to obtain a sensitivity such that a /2. inch layer of the aqueous slurry can be fully detonated by a No. 10 blasting cap, and a inch layer can be fully detonated by a 7 gram cast Pentolite booster. However, a sensitivity to permit complete detonation of a 1 inch layer by a 10 gram cast Pentolite booster is preferred. Pentolite is the preferred explosive sensitizer. Other explosive sensitizers that can be used are pentaerythritol tetranitrate, nitrostarch, and combinations of nitrostarch and Pentolite (a mixture of equal parts by weight of pentaerythritol tetranitrate and trinitrotoluene). Pentolite imparts good sensitivity, and is less sensitive to impact friction than PETN, a desirable property, should the slurry be allowed to dry out at any stage. It is also possible, under certain circum stances, with appropriate adjustment of the amounts of inorganic nitrate oxidizer, to use carbine ball powder, cyclotrimethylene trinitramine (cyclonite, RDX), Composition B (a mixture of up to 60% RDX, up to 40% TNT, and 1 to 4% wax), Cyclotrol (Composition 13 without the Wax), lead azide, lead styphnate, and tetryl. However, many explosive sensitizers are insufiiciently powerful to be useful in the slurries of the invention, and such unsatisfactory sensitizers include trinitrotoluene, dinitrotoluene, nitrocellulose, and trimethylolethane trinitrate.

Sensitizing explosives of any particle size can be used. They can, for example, be fine, coarse, or a blend of fine and coarse material. Some materials, such as nitrostarch, are commercially available as very finely-divided powders, while Pentolite is available in pellets. Such available materials are employed to advantage, because in most cases they tend to produce compositions having a greater sensitivity.

The explosive sensitizer is insoluble in the aqueous slurry, and consequently constitutes the principal suspended ingredient, all of the inorganic nitrate oxidizer being in solution.

To increase power and rate of detonation, a powdered metal can be added, such as aluminum, or ferrosilicon, or magnesium. Any particulate form can be used, such as powder, flake, atomized particles, granules, or pellets. A small amount will give a noticeable improvement. The amount can be within the range from about 0.01 to about 10%, preferably from 0.5 to

For a constant velocity, it is important to maintain a relatively uniform density in the slurry over the stated temperature range. For this purpose, there is incorporated in the slurry an organic amide that is capable of forming a eutectic mixture with the inorganic nitrate or nitrate used. This stabilizes the inorganic nitrate in solution, prevents the formation of different nitrate phases and hydrates phases in solution with change in temperature, and so stabilizes the density. Urea is the preferred organic amide, but also useful are thiourea and formamide, as

4 well as urea derivatives, such as dimethyl urea, monomethyl urea, and diethyl urea.

Water is employed in an amount sufiicient to slurry the amount of explosive sensitizer, and dissolve the amount of inorganic nitrate oxidizer, that are required for the desired velocity. Water has a desensitizing eifect, which increases as the amount of water is increased. Consequently, it is important to keep the amount of Water at the minimum required to dissolve the inorganic nitrate oxidizer. For this purpose, not much water is normally required, and if the amount of oxidizer is small, as little as 7% water by weight of the composition can be sufficient. Usually, the amount of water does not exceed about 25%, and preferably the amount is within the range from about 10 to about 17.5%.

A thickening agent is employed, if necessary to impart a higher viscosity. The amount depends upon the thickening efifect desired, and the thickening eflect of the particular thickener that is used. As is well known, thickeners vary considerably in their effectiveness. Usually, quite small amounts of thickeners sufiice, and the amount of thickener can be within the range from 0.1 to about 5% by Weight of the composition. The thickener is watersoluble or water-dispersible. Preferred thickeners are guar gum and polyacrylamides. It is, however, possible to employ the conventional thickening agents for slurried explosives, such as sodium carboxymethyl cellulose, methyl cellulose, psyllium seed musilage, pregelatinized starches, the alginates, hydrolyzed starch, dextrins and hydroxyethyl cellulose.

A composition in accordance with the invention based solely on explosive sensitizer, inorganic nitrate oxidizer, organic amide, thickeners, and Water, has a relatively high although constant velocity, of the order of 17,000 to 18,000 ft./second. If such velocity is higher than the sonic velocity of the metals being bonded, it is necessary to reduce it, and one way in which this can be done is by adding an inorganic salt that at the time of detonation serves as a coolant to remove heat from the reaction, but does not decompose to give gaseous products. It is possible by addition of a coolant to reduce velocity to and still maintain it constant at as low as 10,000 ft./ second.

Any inorganic or organic salt that is water-insoluble and has a high specific heat is satisfactory. Preferred coolants are metal salts of organic acids, and especially heavy metal salts, such as calcium formate. Also useful are sodium formate, calcium acetate, calcium propionate, barium formate, lead formate, lead acetate, calcium benzoate, sodium acetate, calcium oxalate, calcium tartrate, and sodium citrate. The coolant should be waterinsoluble, so that the particles in the slurry can serve as heat-acceptors, but it need not be, and a sparsely soluble salt can be used, if the amount is Well is excess of that needed to form a saturated solution, so that the undissolved or suspended particles are in an amount Within the stated range over the range of temperatures at which detonation is to be effected.

The amount of coolant salt that is added will depend upon the reduction in velocity that is required to match the sonic velocity of the metal. In many cases, as indicated, no coolant is necessary, but if a coolant is used, the amount can range up to approximately 35% by weight, preferably from about 5 to about 25% by weight.

An antacid, or other stabilizing material, such as Zinc oxide, calcium carbonate, aluminum oxide, and sodium carbonate, can also be added. Such ingredients will comprise from about 0.3 to about 2% of the mixture.

In view of the fact that the slurries of the invention are designed to be detonated in a film or layer A to 1 inch thick, and to give a constant velocity that is intended to match a predetermined sonic velocity of metals being bonded, and it is not possible to predict with precision, by calculation, the velocity of a given slurry, it is necessary to formulate the explosive composition by trial and error, adjusting the types and amounts of explosive sensi tizer, inorganic nitrate oxidizer, amide, and coolant (if needed), to give the required velocity. The best procedure is to begin with a complete formula, such as one of the working examples which follow, having a known velocity at known temperatures, and then adjust the proportions of the components up or down, depending upon whether it is desired to have a higher or a lower velocity than that shown. Further variations are obtained by substituting another nitrate or nitrates for that shown, to modify the density, and by substituting another explosive sensitizer for that shown, to modify sensitivity and velocity. Of course, if the velocity shown is that desired, then it is unnecessary to make any modification whatsoever, unless one or more of the components for some reason is unavailable.

The amount of explosive sensitizer is suflicient to give the necessary sensitivity to accept and sustain detonation by a No. blasting cap in a /2 inch layer thickness, and by a 7 gram pentolite booster in a A inch layer thickness. Such amounts usually lie within the range from about 20 to about 40% sensitizer, by weight of the composition.

The amount of inorganic nitrate oxidizer is chosen together with the amount of explosive sensitizer to give the desired velocity (subject to modification as required by addition of inorganic coolant salt). Accordingly, the amount of inorganic nitrate oxidizer is within the range from about 35 to about 55% by weight.

The inorganic nitrate oxidizer and its amount are to a certain degree correlated with density, because this also affects velocity. Thus, if the velocity is too low, it is possible to increase velocity by increasing the density, using a higher proportion of the inorganic nitrate, or by substituting a heavier inorganic nitrate, and if the velocity is too high, the density can be reduced, by using a lesser proportion of the inorganic nitrate, or by using a lighter inorganic nitrate. In general, satisfactory velocities are obtained at densities within the range from about 1.2 to about 1.85.

The amount of organic amide that is capable of forming a eutectic mixture with the inorganic nitrates is determined by the required amount and solubility of the inorganic nitrate or mixture thereof. The amide aids in keeping the amount of water at a minimum, since it serves the function of forming a eutectic mixture with the nitrate having a higher solubility than the inorganic nitrate, reducing the amount of water necessary to form a solution. Large amounts of the amide are not required, and usually amounts of within the range from about 1 to about 10% are sufficient, but as much as 25% can be used. The amide may have an effect on velocity, and therefore more than is necessary for these purposes should not be used, since this may otherwise upset the balance of the other explosive ingredients.

The explosive slurries of the invention can, if desired, be fired with the aid of a booster charge, or, if the layer is /2 inch or more thick, even with a blasting cap. Any conventional cap-sensitive booster charge available in the art can be employed. Pentaerythritol tetranitrate, Composition B and pentolite are exemplary. The booster charge preferably is non-shock or impact sensitive. The amount of booster charge required depends, of course, upon the amount and sensitivity of the explosive mixture. No. 10 blasting caps are effective with the /2 inch and thicker films.

The explosive mixture is readily prepared by simple mixing of the ingredients. The amide and the inorganic nitrates would usually be mixed first with enough water to form a solution of the inorganic nitrates and the amide. The remaining solid materials, including the sensitizing explosives, antacid, if any, and coolant, if any, then would be mixed together to form a homogeneous blend, and then this mix and the remaining water (if any) would be added, with stirring, followed by addition of thickener, if desired, to bring the slurry to the desired consistency Where cartridges are to be prepared, the consistency is usually comparable to that of a gelled oil or thick, barely pourable mixture, and the mixture is filled or extruded into open-ended containers, using conventional filling or extrusion equipment, to produce the explosive package.

The containers can be formed of any container material not dissolved or attacked by the slurry liquid or liquids. Heavy plastic is inexpensive and available in suflicient thickness of wall, and is therefore preferred. Typical plastic and cellulosic materials which can be used include polyethylene, ethyl cellulose, cellulose acetate, polypropylene, polytetrafluoroethylene, nylon, polyvinyl chloride, polystyrene and polyvinylidene chloride, and nonferrous metals, such as tin, copper and aluminum. Fibrous materials such as wood, paper, and cardboard can be used, if waterproofed or otherwise made resistant to the slurrying liquid.

The following examples in the opinion of the inventors represent preferred embodiments of the slurries of the invention.

EXAMPLE 1 A pelleted Pentolite less than 6 mesh in size was prepared according to the following procedure:

Three pounds of grained trinitrotoluene was melted in a kettle under twelve pounds of water, with stirring, at C. 3.3 pounds of crude pentaerythritol tetranitrate containing 0.31% HNO and 8.6% water was added to the mixture ,and dispersed therein by stirring for thirty minutes at 85 to C. Nine pounds of hot water (90 C.) was added to the mixture, and heating was discontinued. The mixture was stirred while cooling gradually until small pellets of pentolite formed. The mixture was then cooled to 60 C. and filtered, washed with water, and airdried overnight. The acidity of the small (less than 6 mesh) pellets of Pentolite recovered was 0.003% I'INOQ- This pelleted Pentolite was then used in the preparation of an aqueous slurry in accordance with the invention, having the following formulation:

monium nitrate, sodium nitrate and urea together, and then adding the water, forming an aqueous solution of the urea-inorganic nitrates eutectic mixture at room temperature, 25 C. The Pentolite pellets were then stirred in, together with the calcium formate, and after a uniform blend was obtained, the guar gum and polyacrylamide were added, and thoroughly dispersed, forming a viscous, barely fiowable slurry with the inorganic nitrates and urea in solution, and the Pentolite and calcium formate in suspension.

The slurry was formed into a inch thick film, and detonated fully, unconfined, with a No. 10 blasting cap. The velocity was 16,500 feet per second.

The slurry was formed in a inch thick film. This film was not detonated, unconfined, by a No. 10 blasting cap, but it was detonated fully, unconfined, with a 7 gram Pentolite booster. The same velocity was noted.

One-half inch thick layers of this slurry were then shot at temperatures ranging from 30 to F., using No. 10 blasting caps. Throughout this range, the detonation velocity was 16,500 fet per second :250 feet per second. The density of the slurry was 1.50 throughout the temperature range from 30 to 13 F.

EXAMPLE 2 A slurry was prepared, using the same Pentolite as in Example 1, mixed with nitrostarch, and having the following formulation:

This slurry was prepared by mixing the ammonium nitrate, sodium nitrate and urea, and then the water, stirring until a complete solution was obtained at 25 C. Then the Pentolite and nitrostarch were stirred in, followed by the calcium formate and zinc oxide. Finally, the guar gum and polyacrylamide were added, and a uniform viscous but flowable blend obtained.

The density of this slurry was determined over the range from 30 to 130 F., and found to be constant at 1.50.

The slurry was detonated fully, unconfined, in /2 inch layers, using a No. blasting cap, over the temperature range from 30 to 130 F. Throughout this range, the velocity was found to be 15,800 feet per second 250 feet per second.

By reducing the amount of calcium formate in the slurries of Examples 1 and 2, it is possible to increase the detonation velocity. Example 1 without any calcium formate whatsoever detonated in a /2 inch layer, unconfined, with a No. 10 blasting cap, at a detonation velocity of 18,000 feet per second. Example 2 detonated under the same conditions at a detonation velocity of 17,000 feet per second, without the calcium formate.

EXAMPLE 3 An aqueous slurry in accordance with the invention was prepared, having the following formulation:

This composition was prepared by mixing the ammonium nitrate, sodium formate and sodium thiosulfate together, and then adding the water, forming an aqueous solution of the inorganic formate, nitrate and thiosulfate at room temperature, 25 C. The nitrostarch was then stirred in, together with the aluminum, microballoons, and zinc oxide, and after a uniform blend was obtained, the guar gum and sodium carboxymethyl cellulose were added, and thoroughly dispersed, forming a homogeneous, gelatinous, barely fiowable slurry with the inorganic nitrate, formate and thiosulfate in solution, and the nitrostarch, aluminum, microballoons and zinc oxide in suspension.

The slurry was formed into a V2 inch thick film, and detonated fully, unconfined, with 5 g. of 50/50 Pentolite. The velocity was 17,500 feet per second. Ballistic mortar value was 116 (TNT-100). Impact sensitivity was 8 2 kg.- cm.+and 10 kg.-100 cm.+. The density of the slurry was 1.43 throughout the temperature range from 30 to F.

EXAMPLE 4 A formulation was prepared as follows:

Percent Nitrostarch (19-21% H O, dry basis) 40.75 NH NO (mill, grained) n 28.60 Sodium formate 12.00 Zinc oxide 0.80 Aluminum, flake (oiled) 1.75 Guar gum 0.10 Sodium carboxymethyl cellulose 0.55 Sodium thiosulfate, anhydrous 0.30 Phenolic resin microballoons 0.90 H O 14.25

This slurry was prepared by mixing the ammonium nitrate, sodium formate and sodium thiosulfate, and then the water, stirring until a complete solution was obtained at 25 C. Then the nitrostarch was stirred in, followed by the aluminum, microballoons, and zinc oxide. Finally, the guar gum and sodium carboxymethyl cellulose were added, and a uniform viscous gelatinous, flowable blend obtained.

The density of this slurry was determined over the range from 30 to 130 F., and found to be constant at 1.45.

The slurry was detonated fully, unconfined, in V2 inch layers, using 5 g. of 50/50 Pentolite over the temperature range from 30 to 130 F. Throughout this range, the velocity was found to be 15,500 feet per second.

Ballistic mortar value was 112 (TNT-100) and impact sensitivity 2 g.-100 cm.+ to 10 g.-100 c.+.

The sonic velocities of most metals that are bonded by explosive bonding are within the range from 6000 to 18,000 feet per second. Since these formulations have a maximum velocity of 17,000 to 18,00 feet per second, they are suitable for bonding metals having sonic velocities at the upper limit of this range. Also, by appropriate increase of the amounts of calcium formamide (or other inorganic coolant salts) and inorganic nitrates, their velocity can be reduced to as low as 10,000 feet per second, near the lower limit of this range.

Having regard to the foregoing disclosure, the following is claimed as the inventive and patentable embodiments thereof:

1. An aqueous explosive slurry for the explosive bonding of metals which, upon detonation unconfined, in a layer from A to 1 inch thick, has a constant velocity within the range from approximately 15,000 to approximately 20,000 feet per second matching the sonic velocity of a type of metal to be bonded over a wide temperature range, consisting essentially of an aqueous solution of a eutectic mixture of an inorganic nitrate oxidizer and an organic amide and, slurried therein, a particulate organic high expolsive sensitizer, the amount of the inorganic nitrate being within the range from about 35 to about 55% and the amount of the explosive sensitizer being within the range from about 20% to about 40% to give the slurry the sensitivity necessary to accept and sustain detonation by a No. 10 blasting cap in a inch. layer thickness, and by a 7 gram pentolite booster in a inch layer thickness, and a constant velocity over the range from about 15,000 to about 20,000 feet per second; and an inoragnic coolant salt that is water-insoluble and has a high specific heat, in an amount Within the range from 0 to about 35% to reduce the velocity to within the stated range.

2. A slurry in accordance with claim 1 in which the explosive sensitizer is selected from the group consisting of a mixture of equal parts by weight of pentaerythritol tetranitrate and trinitrotoluene, nitrostarch and pentaerythritol tetranitrate.

3. A slurry in accordance with claim 1 in which the slurry has a constant velocity at a temperature within the range from about 25 to about 130 F.

4. A slurry in accordance with claim 1 in which the inorganic coolant is a water-insoluble metal salt of an organic or inorganic acid.

5. A slurry in accordance with claim 1 in which the explosive sensitizer is less than -6 mesh in size.

6. A slurry in accordance with claim 1 in which the aqueous inoragnic nitrate solution is a saturated solution of the inorganic nitrate at the lowest temperature that is likely to be encountered at detonation.

7. A slurry in accordance with claim 1 in which the inorganic nitrate is ammonium nitrate or a mixture thereof with another inorganic nitrate in a minor proportion.

8. A slurry in accordance with claim 1 including a particulate metal in an amount within the range from about 0.01 to about 10% to increase power and rate of detonation.

9. A slurry in accordance with claim 8 in which the metal is aluminum.

10. A slurry in accordance with claim 1 including a water-soluble thickener in an amount within the range from about 0.1 to about 11. A slurry in accordance with claim 10 in which the thickener is a polyacrylamide.

12. A slurry in accordance with claim 10 in which the thickener is guar gum.

13. A slurry in accordance with claim 1 in which the amide is urea.

14. A slurry in accordance with claim 1 in which the amount of water is within the range from about 7 to about 25%.

15. A slurry in accordance with claim 1 in which the amount of coolant is within the range from about 5 to 25 16. A slurry in accordance with claim 1 including an antacid in an amount within the range from about 0.3 to about 2%.

17. A slurry in accordance with claim 1 having the composition:

Percent A mixture of equal parts by weight of pentaerythritol tetranitrate and trinitrotoluene 30:5 NH NO 30:5 NaNO 10 to 15 Urea 2 to 5 Ca(OOCH) 5to 15 Guar gum 0.1 to 1 Polyacrylamide 0.1 to 1 H O mm 20 18. A slurry in accordance with claim 1 having the composition:

19. A slurry in accordance with claim 1 having the composition:

Percent Nitrostarch 401:5 NH NO 30:5 Na(OOCH) 101-5 Zinc oxide 0.1 to 1 Aluminum, flake (oiled) 0.01 to 10 Guar gum 0.1 to 1 Sodium caboxymethyl cellulose 0.1to1 Sodium thiosulfate, anhydrous 0.1 to l Phenolic resin microballoons 0.1 to 5 H2O 1 t0 References Cited UNITED STATES PATENTS 3,238,074 3/ 1966 Griffith et al. 149-2 3,282,752 11/1966 Clay et a1. 149-44 3,347,722 10/ 1967 Gordon 149-41 3,379,587 4/1968 Cook 149-44 3,442,729 5/ 1969 Knight 149-44 3,446,681 5/ 1969 Slykhouse et a1. 149-41 3,451,868 6/1969 Peterson 149-44 BENJAMIN R. PADGETI, Primary Examiner S. J. LECHERT, 111., Assistant Examiner U.S. Cl. X.R.

22 3 UNl'lED STATES PATENT OFFICE CERTIFiCA'lE OF CCRECTICN Patent No. 3,676,234 Dated July 11, 1972 inventor s) William L Schwoy er It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 28 "musilage" should be --mucilage- Column .5 line '74 Period missing before "where" Column 7-, line 1 "fet" should be feet-- Column '7 line 55- "microballons" should be --microballoonsl-- Column 9, line 36, --alb0ut-- is missing before "25%" Claim 15 Column 1 0, line 2'7, caboxyjmethyl" should be -carboxymethyl-- Claim 19 Signed and sealed this 25th day of December 1973.

(SEAL) Attest:

EDWARD M. F ETC ERL JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents l. r e j 33 UNiTED STATES PATENT CFFICE I CETIFICATE @F RECTEUN Patent No. 3, 676, 234 Dated July 11, 1972 II -filer ,i101(s) L- Schwoyer It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 4, line 28 "musilage" should be -'--mucilage-- Period missing before "where" Column 5 line '74 Column 7, line 1, I v "fet" should ,be =--feet-- Column '7 line 55 "microballons" should be --omicroballoonsl-- Column 9, line 36, -+aboutis missing before "25%" Claim 15 l I Column 10, line 27, caboxymetliyl" should be -carboXymethyl--' Claim 19 Signed and sealed this 25th day of December 1973.

' (SEAL) I Attest:

EDWARD M. FLETC ERUR. RENE D. IEG'I'MEYER Attesting Officer Acting Commissionerof Patents I 1 n J 

